Quantification of Protein Secretion from Circulating Tumor Cells in Microfluidic Chambers

Abstract

Cancer cells can be released from a cancerous lesion and migrate into the circulatory system, from whereon they may form metastases at distant sites. Today, it is possible to infer cancer progression and treatment efficacy by determining the number of circulating tumor cells (CTCs) in the patient's blood at multiple time points; further valuable information about CTC phenotypes remains inaccessible. In this article, a microfluidic method for integrated capture, isolation, and analysis of membrane markers as well as quantification of proteins secreted by single CTCs and CTC clusters is introduced. CTCs are isolated from whole blood with extraordinary efficiencies above 95% using dedicated trapping structures that allow co‐capture of functionalized magnetic beads to assess protein secretion. The patform is tested with multiple breast cancer cell lines spiked into human blood and mouse‐model‐derived CTCs. In addition to immunostaining, the secretion level of granulocyte growth stimulating factor (G‐CSF), which is shown to be involved in neutrophil recruitment, is quantified The bead‐based assay provides a limit of detection of 1.5 ng mL−1 or less than 3700 molecules per cell. Employing barcoded magnetic beads, this platform can be adapted for multiplexed analysis and can enable comprehensive functional CTC profiling in the future.

Microfluidic Chip-Based Cancer Diagnosis and Prediction of Relapse by Detecting Circulating Tumor Cells and Circulating Cancer Stem Cells

“…Such recovery of CTCs from the microfluidic device enables further analysis of the captured CTCs, which in turn better informs clinical decisions. Recently, Armbrecht et al introduced another tool to analyze cytokine secretion from captured CTCs within a microfluidic system ( Figure 3 c) [ 75 ]. Using this system, the secretion level of granulocyte colony-stimulating factor (G-CSF), which indicates acute inflammation, was directly quantified.…”

Microfluidic detection of human diseases: From liquid biopsy to COVID-19 diagnosis

“…While isolation techniques are getting mature, the new challenge is whether we can perform analysis on the same chip that we used for isolating the cells. Culturing CTCs for drug screening ( Khoo et al, 2018 ), performing secretome analysis ( Armbrecht et al, 2020 )( Fig. 2 B), and single-cell western blot ( Sinkala et al, 2017 ) on a chip have been explored which greatly emphasized the potential of CTCs for clinical use.…”

“…An integrated system for capture and on-chip secretome analysis of CTCs. Reproduced with permission from ( Armbrecht et al, 2020 ). …”

High‐Throughput Optimization of Recombinant Protein Production in Microfluidic Gel Beads

“…[ 40 ] Furthermore, microfluidic platforms have been combined with next‐generation sequencing and other readouts such as mass spectrometry in order to enable more comprehensive characterization of complex genotype‐secretory phenotype relationships. [ 41–44 ] The abovementioned workflows, while powerful, have several constraints: they require specialized setups (such as droplet sorters), have restricted throughputs (mass spectrometric methods), rely on product‐specific reagents (aptamers, antibodies) or are inherently restricted to a limited product repertoire (enzymes with fluorogenic substrates).…”